4l60E flush

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Camar068

Full Access Member
Air Force Supporting Member
Joined
Feb 5, 2014
Posts
5,038
Reaction score
4,990
Location
Kentucky
First Name
David
Truck Year
1986
Truck Model
K10/LM7 5.3/4L60e/np208/3.73/32"
Engine Size
10 yrs Air Force
My trans lines are cut and have rubber hoses on them. Would it be fine to feed IN new fluid outta one container and OUT old into another out of the other line?

Do this before or after filter change?

Also, thoughts on seafoam trans before hand? I've been a believer of seafoam since a few engines and a 15 yr old walmart weedeater felt like it was gonna blow up cuz I never heard it run so fast after 2 caps of it lol.

When it comes to transmissions tho, I've been afraid to try it.

Thx In Advance
 
Last edited:

CalSgt

Full Access Member
Joined
Oct 3, 2021
Posts
2,276
Reaction score
5,490
Location
CA
First Name
Casey
Truck Year
1980
Truck Model
Chevy K-10 Custom Deluxe
Engine Size
350
The “in” or return line from the cooler doesn’t have suction to pick up the clean fluid. The fluid in the return line just drains into the transmission as it’s pushed by the fluid that’s pumped to the cooler in the feed line.

Drop the pan
Replace filter
Clean and inspect pan
Replace pan
Refill through the dipstick tube
Route the cooler return line into a bucket
Make sure your in Park
Start the truck for a few seconds while a helper keeps watch on the bucket
Fluid will flow from the cooler line
Shut it down and replenish with more clean fluid

Repeat the last two steps until fluid flows clean and red

Reattach cooler line
Check fluid level and add as needed
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
10,082
Reaction score
19,426
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
The way I do it. Do your own,fluid and filter. Put on a pan with a drain plug. Drain and fill the transmission pan just use the drain plug and dipstick tube, leave the pan and cooler alone. Drain once a week for a month,then every other oil change.
 

Old Guy Bill

Supporting Member
Supporting Member
Joined
Sep 10, 2023
Posts
981
Reaction score
2,958
Location
KY
First Name
Bill
Truck Year
1978
Truck Model
K20
Engine Size
400
They used to make a flush spray can for the lines and cooler, it had a fitting for the line. You emptied the entire can to clean any debris out of
it, wasn't for the entire trans & converter though.
 

TotalyHucked

Full Access Member
Joined
Feb 24, 2020
Posts
7,014
Reaction score
26,138
Location
Auburn, Georgia
First Name
Zach
Truck Year
1985
Truck Model
Sierra 1500
Engine Size
5.3
I'm a firm believer in NEVER flushing an auto trans unless you've had it since new and been doing it on a regular interval. EVERY. SINGLE. person I know that's had a 4l60 or anything else flushed was doing a rebuild soon after. All I do is drop the pan, change the filter and top it back up, I've never had an issue.
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
13,967
Reaction score
23,956
Location
Right where I am
First Name
Bagoomba
Truck Year
1981
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
In my years on the round ball flying through space, I am guilty of, and have observed others do the same, interchangeably using "Flush", when they really mean "Drain and Fill".

Yes, the OP did ask about using the cooler lines to recirculate fluid into the transmission, and I guess that is technically a flush, as opposed to simply draining and filling to achieve new fluid in the transmission and torque converter.

If the pan has a drain plug, it's easy to drain and fill. If not, use a pump extractor and suck out the fluid through the fill tube. I did this on my Tahoe and it worked great.

I did 3 gallons on a Sunday afternoon.

Pumped it out, filled it back up, idled the engine for about 10 minutes while shifting through the gears, rinsed and repeated until 3 gallons of new was coursing red through the system. Went from burnt red color to vibrant red. I haven't had the chance to change the filter, but when I do, it'll get a fluid extraction, pan drop, filter change, new gasket, topped off, and ran. This is on my soon to-do list.
 

Camar068

Full Access Member
Air Force Supporting Member
Joined
Feb 5, 2014
Posts
5,038
Reaction score
4,990
Location
Kentucky
First Name
David
Truck Year
1986
Truck Model
K10/LM7 5.3/4L60e/np208/3.73/32"
Engine Size
10 yrs Air Force
In my years on the round ball flying through space, I am guilty of, and have observed others do the same, interchangeably using "Flush", when they really mean "Drain and Fill".

Yes, the OP did ask about using the cooler lines to recirculate fluid into the transmission, and I guess that is technically a flush, as opposed to simply draining and filling to achieve new fluid in the transmission and torque converter.

If the pan has a drain plug, it's easy to drain and fill. If not, use a pump extractor and suck out the fluid through the fill tube. I did this on my Tahoe and it worked great.

I did 3 gallons on a Sunday afternoon.

Pumped it out, filled it back up, idled the engine for about 10 minutes while shifting through the gears, rinsed and repeated until 3 gallons of new was coursing red through the system. Went from burnt red color to vibrant red. I haven't had the chance to change the filter, but when I do, it'll get a fluid extraction, pan drop, filter change, new gasket, topped off, and ran. This is on my soon to-do list.
I'm not getting it.....are you saying I can pull the pan and ALL the fluid is changed? My understanding is about 6 qts of fluid is changed.

Thx Dingo
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
13,967
Reaction score
23,956
Location
Right where I am
First Name
Bagoomba
Truck Year
1981
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
Pan removal does not remove all the fluid. The pan only holds so much, torque converter holds a bunch. So there will be a lot of old fluid left in the system.

With all the different responses to different methods, you got this.
 

Latest posts

Forum statistics

Threads
48,576
Posts
1,071,618
Members
43,129
Latest member
Cletus-33
Top